1. Field of the Invention
The present invention relates to an imaging apparatus and a digital input/output device such as a digital still camera, a video camera, etc.
2. Description of the Related Art
In recent years, imaging apparatuses, such as a digital still camera, using solid state imaging devices are spreading.
Previously, many models of digital still cameras were provided with a function of imaging still pictures. Recently, digital still cameras capable of recording video images with a large recording capacity has become more common as a solid state memory used for a recording medium of the digital still camera has increased in capacity.
On the other hand, higher definition in pictures is desired. In particular, for a digital still camera with a large number of pixels it is desirable to have an imaging lens or, especially, a zoom lens excellent in image formation capability matching with a solid state imaging device with such a large number of pixels and to be configured with small dimensions, and especially thinner in the depth direction.
Further, it is preferable for digital still cameras capable of taking still pictures to have a shape which is thin in a front-to-back direction and long horizontally or vertically for the ease of holding and preventing camera shake at the time of taking a picture. In order to realize such a shape, i.e. thin in the front-to-back direction or in the depth direction, it is preferable to make an imaging optical system thin.
For example, in an imaging optical system disclosed in Japanese Patent Application Publication No. H08-248318, an optical system of a zoom lens, which is constituted by a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth lens group having positive refracting power, is bent by inserting a prism between lenses, thereby thinning a dimension in the optical axis direction.